<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .parent{
            width: 200px;
            height: 200px;
            border: 1px solid orangered;
            display: grid;
            grid-template-rows:repeat(3,50px);
            grid-template-columns:repeat(3,50px);
            /* align-content: center; */
            justify-items: center;
        }
        .item{
            width: 40px;
            height: 40px;
            border: 1px solid black;
            margin-left: -1px;
            margin-top: -1px;
        }
        .parent>div:first-child{
            justify-self: center;
            align-self: center;
        }
    </style>
</head>
<body>
    <div class="parent">
        <div class="item"></div>
        <div class="item"></div>
        <div class="item"></div>
    </div>
</body>
</html>